Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

A system for hybrid broadcast packet replication for virtual local area
networks includes a switch operable to receive a packet with an
associated VLAN identifier and replicate the packet. A VLAN bit mask is
included in the switch to filter the target destinations for the sending
the replicated packets. The mask has a first level that provides to the
switch an indication of a VLAN group where a radio of an AP has an
associated client device. The mask has a second level where the mask
provides to the switch an indication of a WLAN where a radio of an AP has
an associated client device. The mask can have a third level where the
mask provides to the switch an indication of a list of VLANs in use by
each WLAN. The switch can then send those replicated packets filtered
through the mask on to target devices of the identified VLAN.

Claims:

1. A system for hybrid broadcast packet replication for virtual local
area networks, comprising: a switch disposed within at least one wireless
local area network (WLAN), the at least one wireless local area network
comprising at least one virtual local area network (VLAN), the switch
operable to receive a packet with an associated VLAN identifier, wherein
the packet is to be broadcast to at least one target device grouped in
the identified VLAN, the switch also operable to replicate the packet,
and a VLAN bit mask included in the switch, the VLAN bit mask operable to
filter the destinations for the sending of the replicated packets using
the mask, wherein; the mask has a first level that provides to the switch
an indication of a VLAN group where a radio of an AP has an associated
client device, and the mask has a second level where the mask provides to
the switch an indication of a WLAN where a radio of an AP has an
associated client device; and wherein the switch is further operable to
replicate packets based on the mask and send those replicated packets
filtered through the mask on to the at least one target device of the
identified VLAN.

2. The system of claim 1, wherein an identified VLAN exists on more than
one WLAN.

3. The system of claim 1, wherein the mask has a third level where the
mask provides to the switch an indication of a list of VLANs in use by
each WLAN.

4. The system of claim 1, wherein the mask sets one bit for each of the
levels.

5. The system of claim 1, wherein a VLAN bit mask is provided for each
VLAN being served on each WLAN.

6. The system of claim 1, further comprising an access point radio
operable to broadcast those replicated packets filtered through the mask
to the at least one target device of the identified VLAN.

7. A method for hybrid broadcast packet replication for virtual local
area networks, the method comprising the steps of: receiving a packet
with an associated VLAN identifier, wherein the packet is to be broadcast
to at least one target device grouped in the identified VLAN; replicating
the packet based on the destinations for the sending of the replicated
packets using a VLAN bit mask, wherein the mask has a first level that
provides an indication of a VLAN group where a radio of an AP has an
associated client device, and a second level where the mask provides an
indication of a WLAN where a radio of an AP has an associated client
device; and sending those replicated packets filtered through the mask on
to the at least one target device of the identified VLAN.

8. The method of claim 7, wherein the replicating step includes the mask
having a third level where the mask provides an indication of a list of
VLANs in use by each WLAN.

9. The method of claim 7, wherein the replicating step includes the mask
setting one bit for each of the levels.

10. The method of claim 7, wherein the replicating step includes
providing a VLAN bit mask for each VLAN being served on each WLAN.

11. The method of claim 7, further comprising broadcasting those
replicated packets filtered through the mask to the at least one target
device of the identified VLAN.

12. A wireless network switch for hybrid broadcast packet replication for
virtual local area networks, wherein the switch is disposed within at
least one wireless local area network (WLAN) comprising at least one
virtual local area network (VLAN): wherein the switch is operable to
receive a packet with an associated VLAN identifier, wherein the packet
is to be broadcast to at least one target device grouped in the
identified VLAN, the switch is also operable to replicate the packet, and
a VLAN bit mask included in the switch, the VLAN bit mask operable to
filter the destinations for the sending of the replicated packets using
the mask, wherein; the mask has a first level that provides to the switch
an indication of a VLAN group where a radio of an AP has an associated
client device, and the mask has a second level where the mask provides to
the switch an indication of a WLAN where a radio of an AP has an
associated client device; and wherein the switch is further operable to
replicate packets based on the mask send those replicated packets
filtered through the mask on to the at least one target device of the
identified VLAN.

Description:

FIELD OF THE DISCLOSURE

[0001] The present invention relates generally to virtual local area
networks and more particularly to a hybrid technique for broadcast packet
replication for virtual local area networks.

BACKGROUND

[0002] A wireless switched local area network (WLAN) utilizes a switch to
transmit data between various network components. The switch may be
capable of inspecting data packets as they are received, determining the
source and destination device of each packet, and forwarding the packet
appropriately. For example, a switch can send a broadcast packet to all
the access points (APs) under its control to be broadcast to multiple
client devices associated with those access points. The more access
points used, the wider amount of area the network can cover. However,
access points come in different configurations, some of which are more
expensive, e.g. a "fat" access point with its own internal intelligent
processing components, versus a lower cost "thin" access point (or access
port) which only serves to transfer packets. Thus, thin access points may
be used to provide a low cost way to extend an operating coverage area of
the network. However, thin access points are equipped with less
intelligent components than conventional access points, and therefore the
switch must be able to perform the intelligence to make sure that packets
are properly delivered to particular devices, such as devices associated
in a virtual local area network (VLAN). In addition, since thin access
points are low cost, they could be deployed in large numbers, and the
switch will need to manage all of these many thin access points.

[0003] A VLAN is a logical subset of devices in one or more WLAN. Each
wireless LAN may be divided into multiple VLANs. In addition, one VLAN
can extend over multiple WLANs. In one example, it may be desirable to
communicate with a particular logical group of mobile devices. In this
case, a VLAN can be set up with those devices as members of the group.
Packets addressed to members of this group can have an associated field
with an identification or tag of the VLAN contained therein. Ideally,
packets with this VLAN identification will only be exchanged with members
of the VLAN group. However, where a large number of thin APs are used,
and multiple VLANs need to be considered, the switch is required to
manage all these AP, WLAN and VLAN combinations, which requires
considerable resources in the switch and messaging overhead in the air
interface.

[0004] Accordingly, what is needed is a technique for a network switch to
manage WLANs having many thin APs and covering multiple VLANs. It would
also be of benefit to mitigate the replication of unneeded broadcast
packets.

BRIEF DESCRIPTION OF THE FIGURES

[0005] The accompanying figures, where like reference numerals refer to
identical or functionally similar elements throughout the separate views,
together with the detailed description below, are incorporated in and
form part of the specification, and serve to further illustrate
embodiments of concepts that include the claimed invention, and explain
various principles and advantages of those embodiments.

[0006] FIG. 1 is a simplified block view of an apparatus, in accordance
with the present invention.

[0007]FIG. 2 is a simplified flow diagram demonstrating a method, in
accordance with the present invention.

[0008] Skilled artisans will appreciate that elements in the figures are
illustrated for simplicity and clarity and have not necessarily been
drawn to scale. For example, the dimensions of some of the elements in
the figures may be exaggerated relative to other elements to help to
improve understanding of embodiments of the present invention.

[0009] The apparatus and method components have been represented where
appropriate by conventional symbols in the drawings, showing only those
specific details that are pertinent to understanding the embodiments of
the present invention so as not to obscure the disclosure with details
that will be readily apparent to those of ordinary skill in the art
having the benefit of the description herein.

DETAILED DESCRIPTION

[0010] The present invention provides a novel technique for a wireless
network switch to manage multiple wireless local area networks (WLANs)
having many "thin" access points or ports (APs) and covering multiple
virtual LANs (VLANs). The present invention is also able to mitigate the
replication of unneeded broadcast packets. The exemplary embodiments of
the present invention describe a system and method for broadcasting
packets from a wireless switch on a network including multiple WLANs and
multiple VLANs. In particular, the exemplary embodiments of the present
invention provide a switch coupled to multiple thin APs divided into at
least one VLAN and serving a number of client devices. The WLANs
including the wireless switch, VLANs, the APs, and the client devices
will be described in detail below.

[0011] FIG. 1 is a simplified block diagram of various embodiments of the
present invention. Wireless switched LANs (WLANs) are shown. The WLANs
includes a wireless switch 100 modified in accordance with the present
invention. The switch is coupled to a thin access point 102. Although
only one access point (AP) is shown, it should be recognized that the
switch can be coupled to many APs. The thin access points service any
number of client devices 108-112. It should be recognized that the client
devices can move from the service area of one AP to the service area of
another AP, and that the switch can keep track of, and manage, this
movement.

[0012] In practice, it is envisioned that the switch is one of Motorola
Solutions, Inc. WiNG5® switch products such as models RFS4000,
RFS6000, and RFS7000 operable on a IEEE 802.11 protocol and capable of
supporting a thin access port such as Motorola Solutions, Inc. AP300®
access port, or any original equipment manufacture products capable of
supporting both WiNG5® and AP300® products. AP300® access ports
contain two radio sections (as shown) that can operate on two different
frequency bands of 2.4 GHz and 5.2 GHz. In addition, each access port can
support four BSSIDs (Basic Service Set Identifiers) and sixteen ESSIDs
(Extended Service Set Identifiers) per radio, enabling granular
segmentation into multiple WLANs and VLANs.

[0013] According to the exemplary embodiments of the present invention,
multiple VLANs may exist within the one or more WLANs. A VLAN can also
include a portion of an overall wide area network (WAN) in which the
WLANs are included. The VLAN can include a variety of components that may
be selected by a variety of conditions. For example, the VLAN can include
a set of components based on a location. Thus, the components may be
localized in an area. In another example, the VLAN can include a set of
components based on time. Thus, the components may be determined based on
when the device was introduced into the network. In yet another example,
the VLAN can include a set of components based on an available
connectivity. Thus, the components may be selected based on a location
and/or operating area of other components.

[0014] As illustrated, the AP 102 is connected to the switch 100. Each AP
can communicate with the switch using a wireless connection 122. Those
skilled in the art will understand that the physical connection between
an AP and the switch can be either via a WAN port or a LAN port. The APs
are responsible for distribution of broadcast data packets for the VLANs.
As a wireless switched network, APs can wirelessly communicate with the
client devices using one or more WLANs 104, 106. APs can also be
connected to other APs (not shown) using a wired and/or wireless
connection to form a mesh network. This connection may be a local data
path so that data may be transmitted within the VLAN. In the example
shown, AP 102 can wirelessly communicate with client devices 108-112
using either WLAN 1 104 or WLAN 2 106. In this example, AP uses its radio
1 to communicate 120 with client A 108 over WLAN 1 104 where client A is
a member of VLAN group 5. AP also uses its radio 1 to communicate 118
with client B 110 over WLAN 2 106 where client B is a member of VLAN
group 10. AP uses its radio 2 to communicate 114 with client C 112 over
WLAN 2 106 where client C is a member of VLAN group 5.

[0015] AP 102 can include a separate control path (not shown) to the
switch 100. The control paths can be used for transmitting and/or
receiving IEEE 802.11 protocol control packets, which can include secure
configuration information, statistics data, and performance information.
In addition, each AP 102 can include a data path 122 to the switch 100.
Each data path is responsible for distributing broadcast data to the
components of the VLAN.

[0016] For efficiency, it is desired to send broadcast data packets to
only those client devices belonging to a VLAN group indicated for that
packet. For an AP operable on more than one WLAN or having more than one
radio, an incoming broadcast packet to an IEEE 802.11 AP must be
replicated and transmitted on each WLAN and radio. Ideally, a broadcast
packet should only be sent on WLANs that contain an associated client
device of a VLAN matching the VLAN identity of the incoming broadcast
packet. This wastes as little air bandwidth as possible. In order to
provide this efficiency, a VLAN identity tag is included with the
broadcast data packet. The switch can then use a VLAN bit mask to
identify which packets have this VLAN identity tag in order to limit
needless replications and transmissions.

[0017] Ideally, the VLAN bit masks required to properly limit broadcast
replications would be a bit mask of all possible VLANs for each possible
WLAN on each radio. A VLAN bit mask is a 512 byte structure (1 bit per
4096 possible VLANs). In the case of the Motorola Solutions, Inc.
WiNG5® architecture, this equates to sixteen VLAN bit masks per radio
or eight kilobytes worth of data structures per radio. In a standard
"fat" AP architecture, there are few radios and the bit mask size is not
a critical resource. However, in a thin AP architecture, for example
using many Motorola Solutions, Inc. AP300® access ports, requires
those data structures to be present and managed on the switch, which
would need to support the many thin APs. For example, the Motorola
Solutions, Inc. RFS7000® switch can adopt 512 AP300 access ports, each
of which contains two radios. Using the simple data structure layout
describes above, that equates to 2*512*8 k=8192 kilobytes, which is a
significant amount of memory to dedicate on these platforms.

[0018] To preserve memory on platforms that support thin APs, such as the
RFS7000® switch supporting AP300® access points, the present
invention incorporates a novel VLAN hybrid bit mask. This hybrid approach
uses smaller data structures than that of a standard AP architecture. In
particular, the present invention reduces the memory requirement for the
VLAN bit masks from 8 kilobytes per radio to 2.25 kilobytes per radio,
which improves performance and increases the number of devices and
features that can be supported. In operation, the reduced mask size of
present invention sometimes results in the replication and sending of an
unneeded packet, but is configured such that the cases where unneeded
packets are replicated and sent are the result of only unusual
configurations that are not encountered often, as will be detailed below.

[0019] In the simplest embodiment, the switch 100 will have a VLAN bit
mask for each VLAN present on each WLAN. In the example shown in FIG. 1,
the bit mask indicates that there is VLAN group 5 on WLANs 1 and 2, and
that VLAN group 10 is on WLAN 2. Upon receiving a pack to be broadcast to
VLAN group 5, the switch will replicate the broadcast packet, based on
the VLAN bit mask, for both WLAN 1 and 2 which is supplied to both radio
(that support WLANs 1 and 2). The radios will then broadcast 114-120 the
replicated packets. This embodiment does not require a map of any client
devices, but only on which WLAN the target VLAN group is located. As a
result, this embodiment sends out the most number of replicated packets,
even sending out 116 the packet on radio 2 to WLAN 1 104 to no client
device, and on radio 1 to WLAN 2 106 to a client device 110 that is not
part of VLAN 5 and will not accept the packet.

[0020] In an ideal embodiment, the switch 100 will not only have a bit
mask for each VLAN present on each WLAN, but also where the client
devices are on each radio. In the example shown in FIG. 1, the bit mask
indicates that there is VLAN group 5 on WLANs 1 and 2, and that client A
108 of VLAN group 5 is being served by radio 1 on WLAN 1, and that client
C 112 of VLAN group 5 is being served by radio 2 on WLAN 2. Upon
receiving a pack to be broadcast to VLAN group 5, the switch will
replicate the broadcast packet for WLAN 1 104 on radio 1 and WLAN 2 106
on radio 2. The radios will then broadcast 120, 114 the packets on radios
1 and 2, respectively. This embodiment requires a map of client devices,
as well as which WLAN the target VLAN group is located. As a result, this
embodiment sends out the least number of replicated packets, sending
packets 120, 114 to the correct target devices 108, 112 only.

[0021] The present invention provides a hybrid embodiment of a VLAN bit
mask 124 with three levels of masking. The mask will filter the
destinations for the sending of the replicated packets using the mask. At
a first level, the mask provides to the switch an indication of a VLAN
group where a radio of an AP has an associated client device. This first
level indication is provided per radio and uses the VLAN bit mask such
that a bit that is set ON shows that there is at least one client in that
VLAN group that is being served by that radio. At a second level, the
mask provides to the switch an indication of a WLAN where a radio of an
AP has an associated client device. This second level is in effect a WLAN
mask that lists all WLANs and provides a bit that is set ON if there is a
client on a particular radio serving that WLAN. At a third level, the
mask provides to the switch an indication of a list of VLANs in use by
each WLAN. In the above levels, one bit of the mask is set ON or OFF for
each of these three levels.

[0022] Therefore, in the example shown in FIG. 1, the VLAN bit mask of the
hybrid embodiment first indicates that VLAN group 5 has clients on both
radios 1 and 2, and that VLAN group 10 has a client on radio 1. In this
example, the first level filters none of the packets since VLAN 5
components are on both radios. The hybrid embodiment secondly indicates
that there is a client on WLAN 1 using radio 1, and clients on WLAN 2
using radios 1 and 2. In this example, the second level filters any
packets from going to WLAN 1 on radio 2 since there are no clients there.
The hybrid embodiment thirdly indicates that VLAN group 5 is being served
by both WLANs 1 and 2, and that VLAN group 10 is being served by radio 1
on WLAN 2. In this example, the third level does not filter the packets
any further, and the packets will be broadcast 120, 118, 114 respectively
to client A 108, client B 110, and client C 112 even though the packet
sent 118 to client B 110 is unneeded and will not be accepted by that
client.

[0023] This hybrid embodiment does not require a map of client devices,
which is similar to the advantage of the simplest embodiment by saving
memory that otherwise would be needed to map all clients. The hybrid
embodiment also does not send 116 packets to devices that are not
present, which was a problem of the simplest embodiment, and thereby
saves messaging overhead. As can be seen, this hybrid embodiment may send
out some unneeded packets (e.g. to client B 118 which is not part of VLAN
group 5) under certain uncommon circumstances. In particular, the sending
118 of the unnecessary packet is the result of VLAN group 5 overlapping
both WLANs 1 and 2, where two WLANs will get packets for same VLAN, which
is not a normal circumstance since it is more typical that VLANs do not
overlap between WLANs. In the above example, if WLAN 2 only supported
VLAN 10, then packets would only be sent properly to clients A and C.

[0024] It should be noted that a plurality of client devices may be
disposed in each of the VLANs and that these client devices can be
mobile. As a result, the client devices can be connected to any of the
APs, and each AP can forward the packet to any client device connected
thereto. The switch knows the VLAN group of each client device, and
manages where each client device is located in the WLAN, i.e. which AP
and radio is serving which client device. Accordingly, the switch will
know where to direct packets for a particular VLAN.

[0025] As used herein, the switch, APs, and client devices, can comprise
basic components such as, but not limited to, microprocessors, digital
signal processors, microcontrollers, computers, drivers, memory devices,
application-specific integrated circuits, and/or logic circuitry. Such
devices are typically adapted to implement algorithms and/or protocols
that have been expressed using high-level design languages or
descriptions, expressed using computer instructions, expressed using
messaging/signaling flow diagrams, and/or expressed using logic flow
diagrams. Thus, given an algorithm or logic flow, those skilled in the
art are aware of the many design and development techniques available to
implement user equipment that performs the given logic. Therefore, the
processor represents a known apparatus that has been adapted, in
accordance with the description herein, to implement various embodiments
of the present invention.

[0026]FIG. 2 illustrates a flowchart of a method for hybrid broadcast
packet replication for virtual local area networks, in accordance with
the present invention.

[0027] The method starts by receiving 202 a packet with an associated VLAN
identifier, wherein the packet is to be broadcast to at least one target
device grouped in the identified VLAN.

[0028] A next step includes replicating 204 the packet based on the
destinations for the sending of the replicated packets using a VLAN bit
mask. If the mask indicates multiple destinations requiring replication
and sending of the packet, then the packet will be replicated. The mask
has a first level filter that provides an indication of a VLAN group
where a radio of an AP has an associated client device. The mask also has
a second level filter where the mask provides an indication of a WLAN
where a radio of an AP has an associated client device. The mask can also
have a third level where the mask provides an indication of a list of
VLANs in use by each WLAN. The mask reduces memory space by setting one
bit for each of the level filters. This step can also include providing a
VLAN bit mask for each VLAN being served on each WLAN.

[0029] A next step includes sending 208 those replicated packets filtered
through the mask on to the at least one target device of the identified
VLAN.

[0030] A next step includes broadcasting 210 those replicated packets
filtered through the mask to the at least one target device of the
identified VLAN.

[0031] Advantageously, the present invention provides a system that allows
reduces VLAN bit masks size when thin AP architectures are used in a LAN,
which improves performance and increases the number of devices and
features that can be supported.

[0032] In the foregoing specification, specific embodiments have been
described. However, one of ordinary skill in the art appreciates that
various modifications and changes can be made without departing from the
scope of the invention as set forth in the claims below. Accordingly, the
specification and figures are to be regarded in an illustrative rather
than a restrictive sense, and all such modifications are intended to be
included within the scope of present teachings.

[0033] The benefits, advantages, solutions to problems, and any element(s)
that may cause any benefit, advantage, or solution to occur or become
more pronounced are not to be construed as a critical, required, or
essential features or elements of any or all the claims. The invention is
defined solely by the appended claims including any amendments made
during the pendency of this application and all equivalents of those
claims as issued.

[0034] Moreover in this document, relational terms such as first and
second, top and bottom, and the like may be used solely to distinguish
one entity or action from another entity or action without necessarily
requiring or implying any actual such relationship or order between such
entities or actions. The terms "comprises," "comprising," "has",
"having," "includes", "including," "contains", "containing" or any other
variation thereof, are intended to cover a non-exclusive inclusion, such
that a process, method, article, or apparatus that comprises, has,
includes, contains a list of elements does not include only those
elements but may include other elements not expressly listed or inherent
to such process, method, article, or apparatus. An element proceeded by
"comprises . . . a", "has . . . a", "includes . . . a", "contains . . .
a" does not, without more constraints, preclude the existence of
additional identical elements in the process, method, article, or
apparatus that comprises, has, includes, contains the element. The terms
"a" and "an" are defined as one or more unless explicitly stated
otherwise herein. The terms "substantially", "essentially",
"approximately", "about" or any other version thereof, are defined as
being close to as understood by one of ordinary skill in the art, and in
one non-limiting embodiment the term is defined to be within 10%, in
another embodiment within 5%, in another embodiment within 1% and in
another embodiment within 0.5%. The term "coupled" as used herein is
defined as connected, although not necessarily directly and not
necessarily mechanically. A device or structure that is "configured" in a
certain way is configured in at least that way, but may also be
configured in ways that are not listed.

[0035] It will be appreciated that some embodiments may be comprised of
one or more generic or specialized processors (or "processing devices")
such as microprocessors, digital signal processors, customized processors
and field programmable gate arrays and unique stored program instructions
(including both software and firmware) that control the one or more
processors to implement, in conjunction with certain non-processor
circuits, some, most, or all of the functions of the method and/or
apparatus described herein. Alternatively, some or all functions could be
implemented by a state machine that has no stored program instructions,
or in one or more application specific integrated circuits (ASICs), in
which each function or some combinations of certain of the functions are
implemented as custom logic. Of course, a combination of the two
approaches could be used.

[0036] Moreover, an embodiment can be implemented as a computer-readable
storage medium having computer readable code stored thereon for
programming a computer (e.g., comprising a processor) to perform a method
as described and claimed herein. Examples of such computer-readable
storage mediums include, but are not limited to, a hard disk, a CD-ROM,
an optical storage device, a magnetic storage device, a ROM (Read Only
Memory), a PROM (Programmable Read Only Memory), an EPROM (Erasable
Programmable Read Only Memory), an EEPROM (Electrically Erasable
Programmable Read Only Memory) and a Flash memory. Further, it is
expected that one of ordinary skill, notwithstanding possibly significant
effort and many design choices motivated by, for example, available time,
current technology, and economic considerations, when guided by the
concepts and principles disclosed herein will be readily capable of
generating such software instructions and programs with minimal
experimentation.

[0037] The Abstract is provided to allow the reader to quickly ascertain
the nature of the technical disclosure. It is submitted with the
understanding that it will not be used to interpret or limit the scope or
meaning of the claims. In addition, in the foregoing Detailed
Description, it can be seen that various features are grouped together in
various embodiments for the purpose of streamlining the disclosure. This
method of disclosure is not to be interpreted as reflecting an intention
that the claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect, inventive
subject matter lies in less than all features of a single disclosed
embodiment. Thus the following claims are hereby incorporated into the
Detailed Description, with each claim standing on its own as a separately
claimed subject matter.

Patent applications by Jacob Thomas, San Jose, CA US

Patent applications by Puneet Batta, San Jose, CA US

Patent applications by MOTOROLA SOLUTIONS, INC.

Patent applications in class Contiguous regions interconnected by a local area network

Patent applications in all subclasses Contiguous regions interconnected by a local area network